Objective: The objective was to identify factors associated with thrombocytopenia and to assess to what extent thrombocytopenia increases bleeding complications in liver transplant patients. Design: Retrospective study. Setting: Surgical intensive care unit in a university hospital. Patients: One hundred and sixty-one patients admitted to the intensive care unit after liver transplantation. Intervention: None. Measurements and results: Incidence of thrombocytopenia was defined as a platelet count of <50x10(9)/1 for at least 3 consecutive days, associated events for thrombocytopenia or bleeding were identified by a Cox proportional hazard analysis, and blood product consumption was studied. Thrombocytopenia occurred in 104 patients (65%) with a mortality rate of 18% compared with 2% in nonthrombocytopenic patients (p=0.002). Independent associated events for thrombocytopenia were need of dialysis (hazard ratio [HR], 2.30; 95% confidence interval (95% CI), 1.10-4.80) and value of preoperative platelet count (HR, 1.06; 95% CI, 1.01-1.12 by 104 platelet decrease). The unique associated event identified for significant bleeding was sepsis (HR, 34.80; 95% CI, 1.47-153.40). Severe thrombocytopenia led to an excess of blood product consumption (red blood cells and platelets units) during ICU stay. Conclusion: Thrombocytopenia of <50x10(9)/1 for 3 days is frequent after liver transplantation and as such is not an important contributor to bleeding. However, thrombocytopenia does reflect the severity of the postoperative course.